🚀 go-pugleaf

In message <3cb8094b.821453@news.freeserve.net>, Martin Tanton
<martin@shadow.co.uk> writes
>The basic principal is that that when you save as a gif, the colours
>are reduced to a fixed number of your choosing. Any one of these can be
>chosen to be transparent.

Ah! The penny drops - thank you.

>The crucial point is that only one colour can be transparent, so you
>can't create gifs with smooth edges that will simply blend with any
>background colour. The colour to be 'knocked out' has to be pretty
>close to the colour of the background the gif will go over for the
>technique to be effective, otherwise you will get horrible jaggies
>round the image. Unless you're trying to blend the gif with a textured
>or patterned background I wouldn't bother. Just make sure the
>background colour of the gif and the background colour of your web page
>have the same rgb values.


well, I was thinking of "black & white" sketches and charts, like those
at:

        <http://www.westmidlandbirdclub.com/research/bbcbbs/news-3b.htm>

        (NB page still unfinished draft)


where the six smaller maps were originally like the largest.

I suppose I could simply "flood" the white in the originals with the
same background colour as used on the page, but if I ever change that,
or where users are not seeing the background colour, that would be
messy.

(I'd be happy to see how folks would make the large map transparent)

Incidentally, why does saving a 256-colour GIF as a 5-colour GIF
sometimes result in a larger file?
-- 
Andy Mabbett

                        <http://www.holmes2.org/HOLMES2/warning.html>